As semiconductor technologies evolve, three-dimensional integrated circuits emerge as an effective alternative to further reduce the physical size of a semiconductor chip. In a three-dimensional integrated circuit (3DIC), active circuits are fabricated on different wafers and each wafer die is stacked on top of another wafer die using pick-and-place techniques. Much higher density can be achieved by employing vertical stacking of integrated circuits. Furthermore, three-dimensional integrated circuits can achieve smaller form factors, cost-effectiveness, increased performance and lower power consumption.